1
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Manville RW, Hogenkamp D, Abbott GW. Ancient medicinal plant rosemary contains a highly efficacious and isoform-selective KCNQ potassium channel opener. Commun Biol 2023; 6:644. [PMID: 37322081 PMCID: PMC10272180 DOI: 10.1038/s42003-023-05021-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 06/06/2023] [Indexed: 06/17/2023] Open
Abstract
Voltage-gated potassium (Kv) channels in the KCNQ subfamily serve essential roles in the nervous system, heart, muscle and epithelia. Different heteromeric KCNQ complexes likely serve distinct functions in the brain but heteromer subtype-specific small molecules for research or therapy are lacking. Rosemary (Salvia rosmarinus) is an evergreen plant used medicinally for millennia for neurological and other disorders. Here, we report that rosemary extract is a highly efficacious opener of heteromeric KCNQ3/5 channels, with weak effects on KCNQ2/3. Using functional screening we find that carnosic acid, a phenolic diterpene from rosemary, is a potent, highly efficacious, PIP2 depletion-resistant KCNQ3 opener with lesser effects on KCNQ5 and none on KCNQ1 or KCNQ2. Carnosic acid is also highly selective for KCNQ3/5 over KCNQ2/3 heteromers. Medicinal chemistry, in silico docking, and mutagenesis reveal that carboxylate-guanidinium ionic bonding with an S4-5 linker arginine underlies the KCNQ3 opening proficiency of carnosic acid, the effects of which on KCNQ3/5 suggest unique therapeutic potential and a molecular basis for ancient neurotherapeutic use of rosemary.
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Affiliation(s)
- Rían W Manville
- Bioelectricity Laboratory, Dept. of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA
| | - Derk Hogenkamp
- Bioelectricity Laboratory, Dept. of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA
| | - Geoffrey W Abbott
- Bioelectricity Laboratory, Dept. of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA.
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2
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Quint WH, Tadema KCD, Kokke NCCJ, Meester-Smoor MA, Miller AC, Willemsen R, Klaver CCW, Iglesias AI. Post-GWAS screening of candidate genes for refractive error in mutant zebrafish models. Sci Rep 2023; 13:2017. [PMID: 36737489 PMCID: PMC9898536 DOI: 10.1038/s41598-023-28944-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 01/27/2023] [Indexed: 02/05/2023] Open
Abstract
Genome-wide association studies (GWAS) have dissected numerous genetic factors underlying refractive errors (RE) such as myopia. Despite significant insights into understanding the genetic architecture of RE, few studies have validated and explored the functional role of candidate genes within these loci. To functionally follow-up on GWAS and characterize the potential role of candidate genes on the development of RE, we prioritized nine genes (TJP2, PDE11A, SHISA6, LAMA2, LRRC4C, KCNQ5, GNB3, RBFOX1, and GRIA4) based on biological and statistical evidence; and used CRISPR/cas9 to generate knock-out zebrafish mutants. These mutant fish were screened for abnormalities in axial length by spectral-domain optical coherence tomography and refractive status by eccentric photorefraction at the juvenile (2 months) and adult (4 months) developmental stage. We found a significantly increased axial length and myopic shift in refractive status in three of our studied mutants, indicating a potential involvement of the human orthologs (LAMA2, LRRC4C, and KCNQ5) in myopia development. Further, in-situ hybridization studies showed that all three genes are expressed throughout the zebrafish retina. Our zebrafish models provide evidence of a functional role of these three genes in refractive error development and offer opportunities to elucidate pathways driving the retina-to-sclera signaling cascade that leads to myopia.
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Affiliation(s)
- Wim H Quint
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Kirke C D Tadema
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Nina C C J Kokke
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Magda A Meester-Smoor
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Adam C Miller
- Institute of Neuroscience, University of Oregon, Eugene, USA
| | - Rob Willemsen
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Caroline C W Klaver
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Ophthalmology, Radboud University Medical Center, Nijmegen, The Netherlands
- Institute of Molecular and Clinical Ophthalmology Basel, Basel, Switzerland
| | - Adriana I Iglesias
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands.
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands.
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3
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Clark R, Pozarickij A, Hysi PG, Ohno-Matsui K, Williams C, Guggenheim JA. Education interacts with genetic variants near GJD2, RBFOX1, LAMA2, KCNQ5 and LRRC4C to confer susceptibility to myopia. PLoS Genet 2022; 18:e1010478. [PMID: 36395078 PMCID: PMC9671369 DOI: 10.1371/journal.pgen.1010478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 10/14/2022] [Indexed: 11/19/2022] Open
Abstract
Myopia most often develops during school age, with the highest incidence in countries with intensive education systems. Interactions between genetic variants and educational exposure are hypothesized to confer susceptibility to myopia, but few such interactions have been identified. Here, we aimed to identify genetic variants that interact with education level to confer susceptibility to myopia. Two groups of unrelated participants of European ancestry from UK Biobank were studied. A 'Stage-I' sample of 88,334 participants whose refractive error (avMSE) was measured by autorefraction and a 'Stage-II' sample of 252,838 participants who self-reported their age-of-onset of spectacle wear (AOSW) but who did not undergo autorefraction. Genetic variants were prioritized via a 2-step screening process in the Stage-I sample: Step 1 was a genome-wide association study for avMSE; Step 2 was a variance heterogeneity analysis for avMSE. Genotype-by-education interaction tests were performed in the Stage-II sample, with University education coded as a binary exposure. On average, participants were 58 years-old and left full-time education when they were 18 years-old; 35% reported University level education. The 2-step screening strategy in the Stage-I sample prioritized 25 genetic variants (GWAS P < 1e-04; variance heterogeneity P < 5e-05). In the Stage-II sample, 19 of the 25 (76%) genetic variants demonstrated evidence of variance heterogeneity, suggesting the majority were true positives. Five genetic variants located near GJD2, RBFOX1, LAMA2, KCNQ5 and LRRC4C had evidence of a genotype-by-education interaction in the Stage-II sample (P < 0.002) and consistent evidence of a genotype-by-education interaction in the Stage-I sample. For all 5 variants, University-level education was associated with an increased effect of the risk allele. In this cohort, additional years of education were associated with an enhanced effect of genetic variants that have roles including axon guidance and the development of neuronal synapses and neural circuits.
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Affiliation(s)
- Rosie Clark
- School of Optometry & Vision Sciences, Cardiff University, Cardiff, United Kingdom
| | - Alfred Pozarickij
- School of Optometry & Vision Sciences, Cardiff University, Cardiff, United Kingdom
| | - Pirro G. Hysi
- Section of Ophthalmology, School of Life Course Sciences, King’s College London, London, United Kingdom
- Department of Twin Research and Genetic Epidemiology, School of Life Course Sciences, King’s College London, London, United Kingdom
| | - Kyoko Ohno-Matsui
- Department of Ophthalmology and Visual Science, Tokyo Medical and Dental University, Tokyo, Japan
| | - Cathy Williams
- Centre for Academic Child Health, Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, United Kingdom
| | - Jeremy A. Guggenheim
- School of Optometry & Vision Sciences, Cardiff University, Cardiff, United Kingdom
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4
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Manville RW, Redford KE, van der Horst J, Hogenkamp DJ, Jepps TA, Abbott GW. KCNQ5 activation by tannins mediates vasorelaxant effects of barks used in Native American botanical medicine. FASEB J 2022; 36:e22457. [PMID: 35997997 PMCID: PMC9404676 DOI: 10.1096/fj.202200724r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Revised: 06/30/2022] [Accepted: 07/06/2022] [Indexed: 11/11/2022]
Abstract
Tree and shrub barks have been used as folk medicine by numerous cultures across the globe for millennia, for a variety of indications, including as vasorelaxants and antispasmodics. Here, using electrophysiology and myography, we discovered that the KCNQ5 voltage-gated potassium channel mediates vascular smooth muscle relaxant effects of barks used in Native American folk medicine. Bark extracts (1%) from Birch, Cramp Bark, Slippery Elm, White Oak, Red Willow, White Willow, and Wild Cherry each strongly activated KCNQ5 expressed in Xenopus oocytes. Testing of a subset including both the most and the least efficacious extracts revealed that Red Willow, White Willow, and White Oak KCNQ-dependently relaxed rat mesenteric arteries; in contrast, Black Haw bark neither activated KCNQ5 nor induced vasorelaxation. Two compounds common to the active barks (gallic acid and tannic acid) had similarly potent and efficacious effects on both KCNQ5 activation and vascular relaxation, and this together with KCNQ5 modulation by other tannins provides a molecular basis for smooth muscle relaxation effects of Native American folk medicine bark extracts.
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Affiliation(s)
- Rian W. Manville
- Bioelectricity Laboratory, Dept. of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA
| | - Kaitlyn E. Redford
- Bioelectricity Laboratory, Dept. of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA
| | - Jennifer van der Horst
- Department of Biomedical Sciences, Vascular Biology Group, Panum Institute, University of Copenhagen, Copenhagen, Denmark
| | - Derk J. Hogenkamp
- Bioelectricity Laboratory, Dept. of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA
| | - Thomas A. Jepps
- Department of Biomedical Sciences, Vascular Biology Group, Panum Institute, University of Copenhagen, Copenhagen, Denmark
| | - Geoffrey W. Abbott
- Bioelectricity Laboratory, Dept. of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA
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5
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Singh SP, William M, Malavia M, Chu XP. Behavior of KCNQ Channels in Neural Plasticity and Motor Disorders. MEMBRANES 2022; 12:membranes12050499. [PMID: 35629827 PMCID: PMC9143857 DOI: 10.3390/membranes12050499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2022] [Revised: 04/26/2022] [Accepted: 05/03/2022] [Indexed: 02/01/2023]
Abstract
The broad distribution of voltage-gated potassium channels (VGKCs) in the human body makes them a critical component for the study of physiological and pathological function. Within the KCNQ family of VGKCs, these aqueous conduits serve an array of critical roles in homeostasis, especially in neural tissue. Moreover, the greater emphasis on genomic identification in the past century has led to a growth in literature on the role of the ion channels in pathological disease as well. Despite this, there is a need to consolidate the updated findings regarding both the pharmacotherapeutic and pathological roles of KCNQ channels, especially regarding neural plasticity and motor disorders which have the largest body of literature on this channel. Specifically, KCNQ channels serve a remarkable role in modulating the synaptic efficiency required to create appropriate plasticity in the brain. This role can serve as a foundation for clinical approaches to chronic pain. Additionally, KCNQ channels in motor disorders have been utilized as a direction for contemporary pharmacotherapeutic developments due to the muscarinic properties of this channel. The aim of this study is to provide a contemporary review of the behavior of these channels in neural plasticity and motor disorders. Upon review, the behavior of these channels is largely dependent on the physiological role that KCNQ modulatory factors (i.e., pharmacotherapeutic options) serve in pathological diseases.
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6
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Escobedo SE, Stanhope SC, Dong Z, Weake VM. Aging and Light Stress Result in Overlapping and Unique Gene Expression Changes in Photoreceptors. Genes (Basel) 2022; 13:264. [PMID: 35205309 PMCID: PMC8872477 DOI: 10.3390/genes13020264] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 01/26/2022] [Accepted: 01/28/2022] [Indexed: 11/20/2022] Open
Abstract
Advanced age is one of the leading risk factors for vision loss and eye disease. Photoreceptors are the primary sensory neurons of the eye. The extended photoreceptor cell lifespan, in addition to its high metabolic needs due to phototransduction, makes it critical for these neurons to continually respond to the stresses associated with aging by mounting an appropriate gene expression response. Here, we sought to untangle the more general neuronal age-dependent transcriptional signature of photoreceptors with that induced by light stress. To do this, we aged flies or exposed them to various durations of blue light, followed by photoreceptor nuclei-specific transcriptome profiling. Using this approach, we identified genes that are both common and uniquely regulated by aging and light induced stress. Whereas both age and blue light induce expression of DNA repair genes and a neuronal-specific signature of death, both conditions result in downregulation of phototransduction. Interestingly, blue light uniquely induced genes that directly counteract the overactivation of the phototransduction signaling cascade. Lastly, unique gene expression changes in aging photoreceptors included the downregulation of genes involved in membrane potential homeostasis and mitochondrial function, as well as the upregulation of immune response genes. We propose that light stress contributes to the aging transcriptome of photoreceptors, but that there are also other environmental or intrinsic factors involved in age-associated photoreceptor gene expression signatures.
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Affiliation(s)
- Spencer E. Escobedo
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA; (S.E.E.); (S.C.S.); (Z.D.)
| | - Sarah C. Stanhope
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA; (S.E.E.); (S.C.S.); (Z.D.)
| | - Ziyu Dong
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA; (S.E.E.); (S.C.S.); (Z.D.)
| | - Vikki M. Weake
- Department of Biochemistry, Purdue University, West Lafayette, IN 47907, USA; (S.E.E.); (S.C.S.); (Z.D.)
- Purdue University Center for Cancer Research, Purdue University, West Lafayette, IN 47907, USA
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7
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Korkka I, Skottman H, Nymark S. OUP accepted manuscript. Stem Cells Transl Med 2022; 11:753-766. [PMID: 35639962 PMCID: PMC9299513 DOI: 10.1093/stcltm/szac029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 04/09/2022] [Indexed: 11/15/2022] Open
Abstract
Human pluripotent stem cell (hPSC)-derived retinal pigment epithelium (RPE) is extensively used in RPE research, disease modeling, and transplantation therapies. For successful outcomes, a thorough evaluation of their physiological authenticity is a necessity. Essential determinants of this are the different ion channels of the RPE, yet studies evaluating this machinery in hPSC-RPE are scarce. We examined the functionality and localization of potassium (K+) channels in the human embryonic stem cell (hESC)-derived RPE. We observed a heterogeneous pattern of voltage-gated K+ (KV) and inwardly rectifying K+ (Kir) channels. Delayed rectifier currents were recorded from most of the cells, and immunostainings showed the presence of KV1.3 channel. Sustained M-currents were also present in the hESC-RPE, and based on immunostaining, these currents were carried by KCNQ1-KCNQ5 channel types. Some cells expressed transient A-type currents characteristic of native human fetal RPE (hfRPE) and cultured primary RPE and carried by KV1.4 and KV4.2 channels. Of the highly important Kir channels, we found that Kir7.1 is present both at the apical and basolateral membranes of the hESC- and fresh native mouse RPE. Kir currents, however, were recorded only from 14% of the hESC-RPE cells with relatively low amplitudes. Compared to previous studies, our data suggest that in the hESC-RPE, the characteristics of the delayed rectifier and M-currents resemble native adult RPE, while A-type and Kir currents resemble native hfRPE or cultured primary RPE. Overall, the channelome of the RPE is a sensitive indicator of maturity and functionality affecting its therapeutic utility.
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Affiliation(s)
- Iina Korkka
- BioMediTech, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Heli Skottman
- BioMediTech, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
| | - Soile Nymark
- Corresponding author: Soile Nymark, PhD, Faculty of Medicine and Health Technology, Tampere University, Arvo Ylpön katu 34, 33520 Tampere, Finland. Tel: +358 40 849 0009; E-mail:
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8
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Yang Q, Tan QQ, Lan CJ, Lv BZ, Zhou GM, Zhong WQ, Gu ZM, Mao YM, Liao X. The Changes of KCNQ5 Expression and Potassium Microenvironment in the Retina of Myopic Guinea Pigs. Front Physiol 2021; 12:790580. [PMID: 35002772 PMCID: PMC8733613 DOI: 10.3389/fphys.2021.790580] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 12/07/2021] [Indexed: 11/13/2022] Open
Abstract
KCNQ5 is suggestively associated with myopia, but its specific role in the myopic process has not been studied further. The aim of this study was to investigate the expression of potassium channel gene KCNQ5 and the changes of K+ microenvironment within the retina of form deprivation myopia (FDM) guinea pigs. A total of 60 guinea pigs were randomly divided into the normal control (NC) group, the self-control (SC) group, and the form-deprivation (FD) group for different treatments. Molecular assays and immunohistochemistry (IHC) were conducted to measure the expression and distribution of KCNQ5-related gene and protein in the retina. We determined the K+ concentration in the retina. In addition, the possible effects of form deprivation on potassium ionic currents and the pharmacological sensitivity of KCNQ5 activator Retigabine and inhibitor XE991 to the M-current in RPE cells were investigated using the patch-clamp technique. As a result, FD eyes exhibited more myopic refraction and longer AL. The mRNA and protein levels of KCNQ5 significantly decreased in the FD eyes, but the K+ concentration increased. In addition, the M-type K+ current [IK(M)] density decreased in FD RPE cells, and were activated or inhibited in a concentration-dependent manner due to the addition of Retigabine or XE991. Overall, KCNQ5 was significantly downregulated in the retina of FD guinea pigs, which may be associated with the increasing K+ concentration, decreasing IK(M) density, and elongating ocular axis. It suggested that KCNQ5 may play a role in the process of myopia, and the intervention of potassium channels may contribute to the prevention and control of myopia.
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Affiliation(s)
- Qin Yang
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong, China
- Department of Ophthalmology and Optometry, North Sichuan Medical College, Nanchong, China
- The Translational Medicine Research Center and the Hepatobiliary Research Institute (North Sichuan Medical College), Nanchong, China
| | - Qing Qing Tan
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong, China
- Department of Ophthalmology and Optometry, North Sichuan Medical College, Nanchong, China
| | - Chang Jun Lan
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong, China
- Department of Ophthalmology and Optometry, North Sichuan Medical College, Nanchong, China
| | - Bo Zhen Lv
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong, China
| | - Gui Mei Zhou
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong, China
- Department of Ophthalmology and Optometry, North Sichuan Medical College, Nanchong, China
| | - Wei Qi Zhong
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong, China
- Department of Ophthalmology and Optometry, North Sichuan Medical College, Nanchong, China
- The Translational Medicine Research Center and the Hepatobiliary Research Institute (North Sichuan Medical College), Nanchong, China
| | - Zhi Ming Gu
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong, China
- Department of Ophthalmology and Optometry, North Sichuan Medical College, Nanchong, China
- The Translational Medicine Research Center and the Hepatobiliary Research Institute (North Sichuan Medical College), Nanchong, China
| | - Yu Mei Mao
- The Second Affiliated Hospital of Chongqing Medical University, Chongqing, China
| | - Xuan Liao
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong, China
- Department of Ophthalmology and Optometry, North Sichuan Medical College, Nanchong, China
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9
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Larsson JE, Karlsson U, Wu X, Liin SI. Combining endocannabinoids with retigabine for enhanced M-channel effect and improved KV7 subtype selectivity. J Gen Physiol 2021; 152:151732. [PMID: 32365171 PMCID: PMC7398146 DOI: 10.1085/jgp.202012576] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 03/25/2020] [Indexed: 12/22/2022] Open
Abstract
Retigabine is unique among anticonvulsant drugs by targeting the neuronal M-channel, which is composed of KV7.2/KV7.3 and contributes to the negative neuronal resting membrane potential. Unfortunately, retigabine causes adverse effects, which limits its clinical use. Adverse effects may be reduced by developing M-channel activators with improved KV7 subtype selectivity. The aim of this study was to evaluate the prospect of endocannabinoids as M-channel activators, either in isolation or combined with retigabine. Human KV7 channels were expressed in Xenopus laevis oocytes. The effect of extracellular application of compounds with different properties was studied using two-electrode voltage clamp electrophysiology. Site-directed mutagenesis was used to construct channels with mutated residues to aid in the mechanistic understanding of these effects. We find that arachidonoyl-L-serine (ARA-S), a weak endocannabinoid, potently activates the human M-channel expressed in Xenopus oocytes. Importantly, we show that ARA-S activates the M-channel via a different mechanism and displays a different KV7 subtype selectivity compared with retigabine. We demonstrate that coapplication of ARA-S and retigabine at low concentrations retains the effect on the M-channel while limiting effects on other KV7 subtypes. Our findings suggest that improved KV7 subtype selectivity of M-channel activators can be achieved through strategically combining compounds with different subtype selectivity.
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Affiliation(s)
- Johan E Larsson
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Urban Karlsson
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Xiongyu Wu
- Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden
| | - Sara I Liin
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
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10
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KCNQ5 activation is a unifying molecular mechanism shared by genetically and culturally diverse botanical hypotensive folk medicines. Proc Natl Acad Sci U S A 2019; 116:21236-21245. [PMID: 31570602 DOI: 10.1073/pnas.1907511116] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Botanical folk medicines have been used throughout human history to treat common disorders such as hypertension, often with unknown underlying mechanisms. Here, we discovered that hypotensive folk medicines from a genetically diverse range of plant species each selectively activated the vascular-expressed KCNQ5 potassium channel, a feature lacking in the modern synthetic pharmacopeia, whereas nonhypotensive plant extracts did not. Analyzing constituents of the hypotensive Sophora flavescens root, we found that the quinolizidine alkaloid aloperine is a KCNQ-dependent vasorelaxant that potently and isoform-selectively activates KCNQ5 by binding near the foot of the channel voltage sensor. Our findings reveal that KCNQ5-selective activation is a defining molecular mechanistic signature of genetically diverse traditional botanical hypotensives, transcending plant genus and human cultural boundaries. Discovery of botanical KCNQ5-selective potassium channel openers may enable future targeted therapies for diseases including hypertension and KCNQ5 loss-of-function encephalopathy.
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11
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Van Hook MJ, Nawy S, Thoreson WB. Voltage- and calcium-gated ion channels of neurons in the vertebrate retina. Prog Retin Eye Res 2019; 72:100760. [PMID: 31078724 PMCID: PMC6739185 DOI: 10.1016/j.preteyeres.2019.05.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 04/25/2019] [Accepted: 05/01/2019] [Indexed: 02/06/2023]
Abstract
In this review, we summarize studies investigating the types and distribution of voltage- and calcium-gated ion channels in the different classes of retinal neurons: rods, cones, horizontal cells, bipolar cells, amacrine cells, interplexiform cells, and ganglion cells. We discuss differences among cell subtypes within these major cell classes, as well as differences among species, and consider how different ion channels shape the responses of different neurons. For example, even though second-order bipolar and horizontal cells do not typically generate fast sodium-dependent action potentials, many of these cells nevertheless possess fast sodium currents that can enhance their kinetic response capabilities. Ca2+ channel activity can also shape response kinetics as well as regulating synaptic release. The L-type Ca2+ channel subtype, CaV1.4, expressed in photoreceptor cells exhibits specific properties matching the particular needs of these cells such as limited inactivation which allows sustained channel activity and maintained synaptic release in darkness. The particular properties of K+ and Cl- channels in different retinal neurons shape resting membrane potentials, response kinetics and spiking behavior. A remaining challenge is to characterize the specific distributions of ion channels in the more than 100 individual cell types that have been identified in the retina and to describe how these particular ion channels sculpt neuronal responses to assist in the processing of visual information by the retina.
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Affiliation(s)
- Matthew J Van Hook
- Truhlsen Eye Institute, Department of Ophthalmology & Visual Sciences, University of Nebraska Medical Center, Omaha, NE, USA
| | - Scott Nawy
- Truhlsen Eye Institute, Department of Ophthalmology & Visual Sciences, University of Nebraska Medical Center, Omaha, NE, USA; Department Pharmacology & Experimental Neuroscience(2), University of Nebraska Medical Center, Omaha, NE, USA
| | - Wallace B Thoreson
- Truhlsen Eye Institute, Department of Ophthalmology & Visual Sciences, University of Nebraska Medical Center, Omaha, NE, USA; Department Pharmacology & Experimental Neuroscience(2), University of Nebraska Medical Center, Omaha, NE, USA.
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12
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George AK, Singh M, Homme RP, Majumder A, Sandhu HS, Tyagi SC. A hypothesis for treating inflammation and oxidative stress with hydrogen sulfide during age-related macular degeneration. Int J Ophthalmol 2018; 11:881-887. [PMID: 29862191 DOI: 10.18240/ijo.2018.05.26] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Accepted: 03/12/2018] [Indexed: 12/20/2022] Open
Abstract
Age-related macular degeneration (AMD) is a leading cause of blindness and is becoming a global crisis since affected people will increase to 288 million by 2040. Genetics, age, diabetes, gender, obesity, hypertension, race, hyperopia, iris-color, smoking, sun-light and pyroptosis have varying roles in AMD, but oxidative stress-induced inflammation remains a significant driver of pathobiology. Eye is a unique organ as it contains a remarkable oxygen-gradient that generates reactive oxygen species (ROS) which upregulates inflammatory pathways. ROS becomes a source of functional and morphological impairments in retinal pigment epithelium (RPE), endothelial cells and retinal ganglion cells. Reports demonstrated that hydrogen sulfide (H2S) acts as a signaling molecule and that it may treat ailments. Therefore, we propose a novel hypothesis that H2S may restore homeostasis in the eyes thereby reducing damage caused by oxidative injury and inflammation. Since H2S has been shown to be a powerful antioxidant because of its free-radicals' inhibition properties in addition to its beneficial effects in age-related conditions, therefore, patients may benefit from H2S salubrious effects not only by minimizing their oxidant and inflammatory injuries to retina but also by lowering retinal glutamate excitotoxicity.
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Affiliation(s)
- Akash K George
- Eye and Vision Science Laboratory, Department of Physiology, University of Louisville School of Medicine, Louisville, Kentucky 40202, USA.,Department of Physiology, University of Louisville School of Medicine, Louisville, Kentucky 40202, USA
| | - Mahavir Singh
- Eye and Vision Science Laboratory, Department of Physiology, University of Louisville School of Medicine, Louisville, Kentucky 40202, USA.,Department of Physiology, University of Louisville School of Medicine, Louisville, Kentucky 40202, USA
| | - Rubens Petit Homme
- Eye and Vision Science Laboratory, Department of Physiology, University of Louisville School of Medicine, Louisville, Kentucky 40202, USA.,Department of Physiology, University of Louisville School of Medicine, Louisville, Kentucky 40202, USA
| | - Avisek Majumder
- Department of Physiology, University of Louisville School of Medicine, Louisville, Kentucky 40202, USA.,Department of Biochemistry and Molecular Genetics, University of Louisville School of Medicine, Louisville, Kentucky 40202, USA
| | - Harpal S Sandhu
- Department of Ophthalmology and Visual Sciences, University of Louisville School of Medicine, Louisville, Kentucky 40202, USA.,Kentucky Lions Eye Center, University of Louisville School of Medicine, Louisville, Kentucky 40202, USA
| | - Suresh C Tyagi
- Department of Physiology, University of Louisville School of Medicine, Louisville, Kentucky 40202, USA
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13
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Heteromeric K V2/K V8.2 Channels Mediate Delayed Rectifier Potassium Currents in Primate Photoreceptors. J Neurosci 2018; 38:3414-3427. [PMID: 29483285 DOI: 10.1523/jneurosci.2440-17.2018] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 01/18/2018] [Accepted: 02/11/2018] [Indexed: 01/17/2023] Open
Abstract
Silent voltage-gated potassium channel subunits (KVS) interact selectively with members of the KV2 channel family to modify their functional properties. The localization and functional roles of these silent subunits remain poorly understood. Mutations in the KVS subunit, KV8.2 (KCNV2), lead to severe visual impairment in humans, but the basis of these deficits remains unclear. Here, we examined the localization, native interactions, and functional properties of KV8.2-containing channels in mouse, macaque, and human photoreceptors of either sex. In human retina, KV8.2 colocalized with KV2.1 and KV2.2 in cone inner segments and with KV2.1 in rod inner segments. KV2.1 and KV2.2 could be coimmunoprecipitated with KV8.2 in retinal lysates indicating that these subunits likely interact directly. Retinal KV2.1 was less phosphorylated than cortical KV2.1, a difference expected to alter the biophysical properties of these channels. Using voltage-clamp recordings and pharmacology, we provide functional evidence for Kv2-containing channels in primate rods and cones. We propose that the presence of KV8.2, and low levels of KV2.1 phosphorylation shift the activation range of KV2 channels to align with the operating range of rod and cone photoreceptors. Our data indicate a role for KV2/KV8.2 channels in human photoreceptor function and suggest that the visual deficits in patients with KCNV2 mutations arise from inadequate resting activation of KV channels in rod and cone inner segments.SIGNIFICANCE STATEMENT Mutations in a voltage-gated potassium channel subunit, KV8.2, underlie a blinding inherited photoreceptor dystrophy, indicating an important role for these channels in human vision. Here, we have defined the localization and subunit interactions of KV8.2 channels in primate photoreceptors. We show that the KV8.2 subunit interacts with different Kv2 channels in rods and cones, giving rise to potassium currents with distinct functional properties. Our results provide a molecular basis for retinal dysfunction in patients with mutations in the KCNV2 gene encoding KV8.2.
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14
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Restoration of patterned vision with an engineered photoactivatable G protein-coupled receptor. Nat Commun 2017; 8:1862. [PMID: 29192252 PMCID: PMC5709376 DOI: 10.1038/s41467-017-01990-7] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 10/27/2017] [Indexed: 12/21/2022] Open
Abstract
Retinitis pigmentosa results in blindness due to degeneration of photoreceptors, but spares other retinal cells, leading to the hope that expression of light-activated signaling proteins in the surviving cells could restore vision. We used a retinal G protein-coupled receptor, mGluR2, which we chemically engineered to respond to light. In retinal ganglion cells (RGCs) of blind rd1 mice, photoswitch-charged mGluR2 (“SNAG-mGluR2”) evoked robust OFF responses to light, but not in wild-type retinas, revealing selectivity for RGCs that have lost photoreceptor input. SNAG-mGluR2 enabled animals to discriminate parallel from perpendicular lines and parallel lines at varying spacing. Simultaneous viral delivery of the inhibitory SNAG-mGluR2 and excitatory light-activated ionotropic glutamate receptor LiGluR yielded a distribution of expression ratios, restoration of ON, OFF and ON-OFF light responses and improved visual acuity. Thus, SNAG-mGluR2 restores patterned vision and combinatorial light response diversity provides a new logic for enhanced-acuity retinal prosthetics. To restore sight after retinal degeneration, one approach is to express light-sensitive proteins in remaining cells. Here the authors combine a light-sensitive engineered G protein-coupled receptor and ion channels to restore ON and OFF responses as well as superior visual pattern discrimination.
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15
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Genetic Association Study of KCNQ5 Polymorphisms with High Myopia. BIOMED RESEARCH INTERNATIONAL 2017; 2017:3024156. [PMID: 28884119 PMCID: PMC5572591 DOI: 10.1155/2017/3024156] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 06/10/2017] [Accepted: 07/17/2017] [Indexed: 02/05/2023]
Abstract
Identification of genetic variations related to high myopia may advance our knowledge of the etiopathogenesis of refractive error. This study investigated the role of potassium channel gene (KCNQ5) polymorphisms in high myopia. We performed a case-control study of 1563 unrelated Han Chinese subjects (809 cases of high myopia and 754 emmetropic controls). Five tag single-nucleotide polymorphisms (SNPs) of KCNQ5 were genotyped, and association testing with high myopia was conducted using logistic regression analysis adjusted for sex and age to give Pasym values, and multiple comparisons were corrected by permutation test to give Pemp values. All five noncoding SNPs were associated with high myopia. The SNP rs7744813, previously shown to be associated with refractive error and myopia in two GWAS, showed an odds ratio of 0.75 (95% CI 0.63-0.90; Pemp = 0.0058) for the minor allele. The top SNP rs9342979 showed an odds ratio of 0.75 (95% CI 0.64-0.89; Pemp = 0.0045) for the minor allele. Both SNPs are located within enhancer histone marks and DNase-hypersensitive sites. Our data support the involvement of KCNQ5 gene polymorphisms in the genetic susceptibility to high myopia and further exploration of KCNQ5 as a risk factor for high myopia.
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16
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Tideman JWL, Fan Q, Polling JR, Guo X, Yazar S, Khawaja A, Höhn R, Lu Y, Jaddoe VWV, Yamashiro K, Yoshikawa M, Gerhold-Ay A, Nickels S, Zeller T, He M, Boutin T, Bencic G, Vitart V, Mackey DA, Foster PJ, MacGregor S, Williams C, Saw SM, Guggenheim JA, Klaver CCW. When do myopia genes have their effect? Comparison of genetic risks between children and adults. Genet Epidemiol 2016; 40:756-766. [PMID: 27611182 DOI: 10.1002/gepi.21999] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 07/05/2016] [Accepted: 07/17/2016] [Indexed: 01/10/2023]
Abstract
Previous studies have identified many genetic loci for refractive error and myopia. We aimed to investigate the effect of these loci on ocular biometry as a function of age in children, adolescents, and adults. The study population consisted of three age groups identified from the international CREAM consortium: 5,490 individuals aged <10 years; 5,000 aged 10-25 years; and 16,274 aged >25 years. All participants had undergone standard ophthalmic examination including measurements of axial length (AL) and corneal radius (CR). We examined the lead SNP at all 39 currently known genetic loci for refractive error identified from genome-wide association studies (GWAS), as well as a combined genetic risk score (GRS). The beta coefficient for association between SNP genotype or GRS versus AL/CR was compared across the three age groups, adjusting for age, sex, and principal components. Analyses were Bonferroni-corrected. In the age group <10 years, three loci (GJD2, CHRNG, ZIC2) were associated with AL/CR. In the age group 10-25 years, four loci (BMP2, KCNQ5, A2BP1, CACNA1D) were associated; and in adults 20 loci were associated. Association with GRS increased with age; β = 0.0016 per risk allele (P = 2 × 10-8 ) in <10 years, 0.0033 (P = 5 × 10-15 ) in 10- to 25-year-olds, and 0.0048 (P = 1 × 10-72 ) in adults. Genes with strongest effects (LAMA2, GJD2) had an early effect that increased with age. Our results provide insights on the age span during which myopia genes exert their effect. These insights form the basis for understanding the mechanisms underlying high and pathological myopia.
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Affiliation(s)
- J Willem L Tideman
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Qiao Fan
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
| | - Jan Roelof Polling
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Orthoptics, School of Applied Science Utrecht, Rotterdam, The Netherlands
| | - Xiaobo Guo
- Department of Statistical Science, School of Mathematics & Computational Science, Sun Yat-Sen University, Guangzhou, GD, China
- SYSU-CMU Shunde International Joint Research Institute, Guangzhou, GD, China
- Southern China Research Center of Statistical Science, Sun Yat-Sen University, Guangzhou, GD, China
| | - Seyhan Yazar
- Centre for Ophthalmology and Visual Science, Lions Eye Institute, University of Western Australia, Perth, Western Australia, Australia
| | - Anthony Khawaja
- Department of Public Health and Primary Care, Institute of Public Health, University of Cambridge School of Clinical Medicine, Cambridge, United Kingdom
| | - René Höhn
- Department of Ophthalmology, University Medical Center, Mainz, Germany
- Department of Ophthalmology, Inselspital, Bern, Switzerland
| | - Yi Lu
- Statistical Genetics, QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Vincent W V Jaddoe
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Kenji Yamashiro
- Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Munemitsu Yoshikawa
- Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Aslihan Gerhold-Ay
- Institute of Medical Biostatistics, Epidemiology and Informatics, University Medical Center Mainz, Mainz, Germany
| | - Stefan Nickels
- Department of Ophthalmology, University Medical Center, Mainz, Germany
| | - Tanja Zeller
- Clinic for General and Interventional Cardiology, University Heart Center Hamburg, Hamburg, Germany
| | - Mingguang He
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Australia
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China
| | - Thibaud Boutin
- Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - Goran Bencic
- Department of Ophthalmology, Sisters of Mercy University Hospital, Zagreb, Croatia
| | - Veronique Vitart
- Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - David A Mackey
- Centre for Ophthalmology and Visual Science, Lions Eye Institute, University of Western Australia, Perth, Western Australia, Australia
| | - Paul J Foster
- NIHR Biomedical Research Centre, Moorfields Eye Hospital NHS Foundation Trust & UCL Institute of Ophthalmology, London, United Kingdom
| | - Stuart MacGregor
- Statistical Genetics, QIMR Berghofer Medical Research Institute, Brisbane, Australia
| | - Cathy Williams
- School of Social and Community Medicine, University of Bristol, Bristol, England
| | - Seang Mei Saw
- Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
- National University of Singapore Saw Swee Hock School of Public Health, Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
| | | | - Caroline C W Klaver
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, The Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, The Netherlands
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17
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Liao X, Lan C, Liao D, Tian J, Huang X. Exploration and detection of potential regulatory variants in refractive error GWAS. Sci Rep 2016; 6:33090. [PMID: 27604318 PMCID: PMC5015044 DOI: 10.1038/srep33090] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 08/19/2016] [Indexed: 11/19/2022] Open
Abstract
Refractive error (RE) is a complex multifactorial disease. Genome-wide association studies (GWAS) have provided significant insight into the genetic architecture and identified plenty of robust genetic variations or single nucleotide polymorphisms (SNPs) associated with complex disease. A major current challenge is to convert those resources into causal variants and target genes. We used RegulomeDB and HaploReg to annotate regulatory information onto associated SNPs derived from the two largest RE GWAS, and additional SNPs in linkage disequilibrium (LD) with GWAS significant SNPs. Overall 868 SNPs were investigated, out of which 662 returned RegulomeDB scores of 1 to 6. It was observed that 36 out of those SNPs show strong evidence of regulatory effects with a RegulomeDB score of 1, while only four of them were GWAS significant SNPs (CD55/rs1652333, CNDP2/rs12971120, RDH5/rs3138142 and rs3138144). The results encourage us to explore those putative pathogenic variants, both GWAS significant SNPs as well as the SNPs in LD, for future discernment of functional consequence. This study offers the attractive approach for prioritizing potential functional variants by combining ENCODE data and GWAS information, and provide further insights into the pathogenesis and mechanism and ultimately therapeutics.
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Affiliation(s)
- Xuan Liao
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong 637007, Sichuan Province, China
- Department of Ophthalmology and Optometry, North Sichuan Medical College, Nanchong 637007, Sichuan Province, China
| | - ChangJun Lan
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong 637007, Sichuan Province, China
- Department of Ophthalmology and Optometry, North Sichuan Medical College, Nanchong 637007, Sichuan Province, China
| | - Dan Liao
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong 637007, Sichuan Province, China
- Department of Ophthalmology and Optometry, North Sichuan Medical College, Nanchong 637007, Sichuan Province, China
| | - Jing Tian
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong 637007, Sichuan Province, China
- Department of Ophthalmology and Optometry, North Sichuan Medical College, Nanchong 637007, Sichuan Province, China
| | - XiuQi Huang
- Department of Ophthalmology, Affiliated Hospital of North Sichuan Medical College, Nanchong 637007, Sichuan Province, China
- Department of Ophthalmology and Optometry, North Sichuan Medical College, Nanchong 637007, Sichuan Province, China
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18
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KCNQ potassium channels in sensory system and neural circuits. Acta Pharmacol Sin 2016; 37:25-33. [PMID: 26687932 DOI: 10.1038/aps.2015.131] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 11/10/2015] [Indexed: 12/15/2022] Open
Abstract
M channels, an important regulator of neural excitability, are composed of four subunits of the Kv7 (KCNQ) K(+) channel family. M channels were named as such because their activity was suppressed by stimulation of muscarinic acetylcholine receptors. These channels are of particular interest because they are activated at the subthreshold membrane potentials. Furthermore, neural KCNQ channels are drug targets for the treatments of epilepsy and a variety of neurological disorders, including chronic and neuropathic pain, deafness, and mental illness. This review will update readers on the roles of KCNQ channels in the sensory system and neural circuits as well as discuss their respective mechanisms and the implications for physiology and medicine. We will also consider future perspectives and the development of additional pharmacological models, such as seizure, stroke, pain and mental illness, which work in combination with drug-design targeting of KCNQ channels. These models will hopefully deepen our understanding of KCNQ channels and provide general therapeutic prospects of related channelopathies.
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19
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Caminos E, Vaquero CF, Martinez-Galan JR. Relationship between rat retinal degeneration and potassium channel KCNQ5 expression. Exp Eye Res 2014; 131:1-11. [PMID: 25499209 DOI: 10.1016/j.exer.2014.12.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Revised: 12/02/2014] [Accepted: 12/09/2014] [Indexed: 11/29/2022]
Abstract
KCNQ5/Kv7.5 is a low-threshold non-inactivating voltage-gated potassium channel preferentially targeted to excitatory endings in brain neurons. The M-type current is mediated by KCNQ5 channel subunits in monkey retinal pigment epithelium cells and in brain neurons. This study was undertaken to analyze KCNQ5 expression and the interaction signals of KCNQ5 with other proteins in normal rat retina and during photoreceptor degeneration. The KCNQ5 expression pattern was studied by immunocytochemistry and Western blot in normal rat retinas (Sprague-Dawley, SD) and P23H-1 rats as a retinitis pigmentosa model. The physical interactions of KCNQ5 with calmodulin (CaM), vesicular glutamate transporter 1 (VGluT1) and glial fibrillary acidic protein (GFAP) were analyzed by in situ proximity ligation assays and were supported by calcium recording. KCNQ5 expression was found in the plexiform layers, ganglion cell layer and basal membrane of the retinal pigment epithelium. The physical interactions among KCNQ5 and CaM, VGluT1 and GFAP changed with age and during retinal degeneration. The maximal level of KCNQ5/CaM interaction was found when photoreceptors had almost completely disappeared; the KCNQ5/VGluT1 interaction signal decreased and the KCNQ5/GFAP interaction increased in the inner retina, while degeneration progressed. The basal calcium levels in the astrocytes and neurons of P23H-1 were higher than in the control SD retinas. This study demonstrates that KCNQ5 is present in the rat retina where its activity may be moderated by CaM. Retinal degeneration progression in P23H-1 rats can be followed by an interaction between KCNQ5 with CaM in an in situ system. The relationship between KCNQ5 and VGluT1 or GFAP needs to be more cautiously interpreted.
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Affiliation(s)
- Elena Caminos
- School of Medicine and Institute for Research in Neurological Disabilities (IDINE), University of Castilla-La Mancha, Albacete, Spain.
| | - Cecilia F Vaquero
- School of Medicine and Regional Center for Biomedical Research (CRIB), University of Castilla-La Mancha, Albacete, Spain.
| | - Juan R Martinez-Galan
- School of Medicine and Institute for Research in Neurological Disabilities (IDINE), University of Castilla-La Mancha, Albacete, Spain.
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20
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Simpson CL, Wojciechowski R, Oexle K, Murgia F, Portas L, Li X, Verhoeven VJM, Vitart V, Schache M, Hosseini SM, Hysi PG, Raffel LJ, Cotch MF, Chew E, Klein BEK, Klein R, Wong TY, van Duijn CM, Mitchell P, Saw SM, Fossarello M, Wang JJ, Polašek O, Campbell H, Rudan I, Oostra BA, Uitterlinden AG, Hofman A, Rivadeneira F, Amin N, Karssen LC, Vingerling JR, Döring A, Bettecken T, Bencic G, Gieger C, Wichmann HE, Wilson JF, Venturini C, Fleck B, Cumberland PM, Rahi JS, Hammond CJ, Hayward C, Wright AF, Paterson AD, Baird PN, Klaver CCW, Rotter JI, Pirastu M, Meitinger T, Bailey-Wilson JE, Stambolian D. Genome-wide meta-analysis of myopia and hyperopia provides evidence for replication of 11 loci. PLoS One 2014; 9:e107110. [PMID: 25233373 PMCID: PMC4169415 DOI: 10.1371/journal.pone.0107110] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Accepted: 08/12/2014] [Indexed: 01/01/2023] Open
Abstract
Refractive error (RE) is a complex, multifactorial disorder characterized by a mismatch between the optical power of the eye and its axial length that causes object images to be focused off the retina. The two major subtypes of RE are myopia (nearsightedness) and hyperopia (farsightedness), which represent opposite ends of the distribution of the quantitative measure of spherical refraction. We performed a fixed effects meta-analysis of genome-wide association results of myopia and hyperopia from 9 studies of European-derived populations: AREDS, KORA, FES, OGP-Talana, MESA, RSI, RSII, RSIII and ERF. One genome-wide significant region was observed for myopia, corresponding to a previously identified myopia locus on 8q12 (p = 1.25×10(-8)), which has been reported by Kiefer et al. as significantly associated with myopia age at onset and Verhoeven et al. as significantly associated to mean spherical-equivalent (MSE) refractive error. We observed two genome-wide significant associations with hyperopia. These regions overlapped with loci on 15q14 (minimum p value = 9.11×10(-11)) and 8q12 (minimum p value 1.82×10(-11)) previously reported for MSE and myopia age at onset. We also used an intermarker linkage- disequilibrium-based method for calculating the effective number of tests in targeted regional replication analyses. We analyzed myopia (which represents the closest phenotype in our data to the one used by Kiefer et al.) and showed replication of 10 additional loci associated with myopia previously reported by Kiefer et al. This is the first replication of these loci using myopia as the trait under analysis. "Replication-level" association was also seen between hyperopia and 12 of Kiefer et al.'s published loci. For the loci that show evidence of association to both myopia and hyperopia, the estimated effect of the risk alleles were in opposite directions for the two traits. This suggests that these loci are important contributors to variation of refractive error across the distribution.
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Affiliation(s)
- Claire L. Simpson
- National Human Genome Research Institute, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Robert Wojciechowski
- National Human Genome Research Institute, National Institutes of Health, Baltimore, Maryland, United States of America
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America
| | - Konrad Oexle
- Institute of Human Genetics, Technische Universität München, Munich, Germany
| | - Federico Murgia
- Institute of Population Genetics, National Research Council of Italy, Sassari, Italy
| | - Laura Portas
- Institute of Population Genetics, National Research Council of Italy, Sassari, Italy
| | - Xiaohui Li
- Institute for Translational Genomics and Population Sciences, Los Angeles BioMedical Research Institute at Harbor-UCLA Medical Center, Torrance, California, United States of America
| | - Virginie J. M. Verhoeven
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, the Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Veronique Vitart
- MRC Human Genetics Unit, IGMM, University of Edinburgh, Edinburgh, United Kingdom
| | - Maria Schache
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Australia
| | - S. Mohsen Hosseini
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada, and DCCT/EDIC Research Group, The Diabetes Control and Complications Trial and Follow-up Study, The Biostatistics Center, The George Washington University, Rockville, Maryland, United States of America
| | - Pirro G. Hysi
- Department of Twin Research & Genetic Epidemiology, King's College London, St Thomas' Hospital, London, United Kingdom
| | - Leslie J. Raffel
- Medical Genetics Institute, Cedars-Sinai Medical Center, Los Angeles, California, United States of America
| | - Mary Frances Cotch
- Division of Epidemiology and Clinical Applications, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Emily Chew
- Division of Epidemiology and Clinical Applications, National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Barbara E. K. Klein
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
| | - Ronald Klein
- Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America
| | - Tien Yin Wong
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Australia
- Singapore Eye Research Institute, National University of Singapore, Singapore, Singapore
| | | | - Paul Mitchell
- Centre for Vision Research, Department of Ophthalmology and Westmead Millennium Institute, University of Sydney, Sydney, Australia
| | - Seang Mei Saw
- Department of Epidemiology and Public Health, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Maurizio Fossarello
- Dipartimento di Scienze Chirurgiche, Clinica Oculistica Universita' degli studi di Cagliari, Cagliari, Italy
| | - Jie Jin Wang
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Australia
- Centre for Vision Research, Department of Ophthalmology and Westmead Millennium Institute, University of Sydney, Sydney, Australia
| | - DCCT/EDIC Research Group
- The Diabetes Control and Complications Trial and Follow-up Study, The Biostatistics Center, The George Washington University, Rockville, Maryland, United States of America
| | - Ozren Polašek
- Croatian Centre for Global Health, University of Split Medical School, Split, Croatia
| | - Harry Campbell
- Centre for Population Health Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Igor Rudan
- Centre for Population Health Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Ben A. Oostra
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, the Netherlands
| | - André G. Uitterlinden
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, the Netherlands
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam, the Netherlands
- Netherlands Consortium for Healthy Ageing, Netherlands Genomics Initiative, The Hague, the Netherlands
| | - Albert Hofman
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, the Netherlands
- Netherlands Consortium for Healthy Ageing, Netherlands Genomics Initiative, The Hague, the Netherlands
| | - Fernando Rivadeneira
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, the Netherlands
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam, the Netherlands
- Netherlands Consortium for Healthy Ageing, Netherlands Genomics Initiative, The Hague, the Netherlands
| | - Najaf Amin
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Lennart C. Karssen
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Johannes R. Vingerling
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, the Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Angela Döring
- Institute of Epidemiology, Helmholtz Zentrum München, Neuherberg, Germany
| | - Thomas Bettecken
- Institute of Human Genetics, Helmholtz Zentrum München, Neuherberg, Germany
| | - Goran Bencic
- Department of Ophthalmology, Hospital “Sestre Milosrdnice”, Zagreb, Croatia
| | - Christian Gieger
- Institute of Genetic Epidemiology, Helmholtz Zentrum München, Neuherberg, Germany
| | - H.-Erich Wichmann
- Institute of Epidemiology, Helmholtz Zentrum München, Neuherberg, Germany
| | - James F. Wilson
- Centre for Population Health Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Cristina Venturini
- Department of Twin Research & Genetic Epidemiology, King's College London, St Thomas' Hospital, London, United Kingdom
| | - Brian Fleck
- Princess Alexandra Eye Pavilion, Edinburgh, United Kingdom
| | - Phillippa M. Cumberland
- MRC Centre of Epidemiology for Child Health, Institute of Child Health, University College London, London, United Kingdom
| | - Jugnoo S. Rahi
- MRC Centre of Epidemiology for Child Health, Institute of Child Health, University College London, London, United Kingdom
- Institute of Ophthalmology, University College London, London, United Kingdom
- Ulverscroft Vision Research Group, Institute of Child Health, University College London, London, United Kingdom
| | - Chris J. Hammond
- Department of Twin Research & Genetic Epidemiology, King's College London, St Thomas' Hospital, London, United Kingdom
| | - Caroline Hayward
- MRC Human Genetics Unit, IGMM, University of Edinburgh, Edinburgh, United Kingdom
| | - Alan F. Wright
- MRC Human Genetics Unit, IGMM, University of Edinburgh, Edinburgh, United Kingdom
| | - Andrew D. Paterson
- Program in Genetics and Genome Biology, The Hospital for Sick Children, Toronto, Ontario, Canada, and DCCT/EDIC Research Group, The Diabetes Control and Complications Trial and Follow-up Study, The Biostatistics Center, The George Washington University, Rockville, Maryland, United States of America
| | - Paul N. Baird
- Centre for Eye Research Australia, University of Melbourne, Royal Victorian Eye and Ear Hospital, Melbourne, Australia
| | - Caroline C. W. Klaver
- Department of Ophthalmology, Erasmus Medical Center, Rotterdam, the Netherlands
- Department of Epidemiology, Erasmus Medical Center, Rotterdam, the Netherlands
| | - Jerome I. Rotter
- Institute for Translational Genomics and Population Sciences, Los Angeles BioMedical Research Institute at Harbor-UCLA Medical Center, Torrance, California, United States of America
| | - Mario Pirastu
- Institute of Population Genetics, National Research Council of Italy, Sassari, Italy
| | - Thomas Meitinger
- Institute of Human Genetics, Technische Universität München, Munich, Germany
- Institute of Human Genetics, Helmholtz Zentrum München, Neuherberg, Germany
| | - Joan E. Bailey-Wilson
- National Human Genome Research Institute, National Institutes of Health, Baltimore, Maryland, United States of America
| | - Dwight Stambolian
- Department of Ophthalmology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
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21
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Ion channels and transporters of the retinal pigment epithelium. Exp Eye Res 2014; 126:27-37. [DOI: 10.1016/j.exer.2014.05.005] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Revised: 05/02/2014] [Accepted: 05/12/2014] [Indexed: 12/19/2022]
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22
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Hedegaard ER, Nielsen BD, Kun A, Hughes AD, Krøigaard C, Mogensen S, Matchkov VV, Fröbert O, Simonsen U. KV 7 channels are involved in hypoxia-induced vasodilatation of porcine coronary arteries. Br J Pharmacol 2014; 171:69-82. [PMID: 24111896 DOI: 10.1111/bph.12424] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 07/08/2013] [Accepted: 09/04/2013] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND AND PURPOSE Hypoxia causes vasodilatation of coronary arteries, but the underlying mechanisms are poorly understood. We hypothesized that hypoxia reduces intracellular Ca(2+) concentration ([Ca(2+)](i)) by opening of K channels and release of H₂S. EXPERIMENTAL APPROACH Porcine coronary arteries without endothelium were mounted for measurement of isometric tension and [Ca(2+)](i), and the expression of voltage-gated K channels K(V)7 channels (encoded by KCNQ genes) and large-conductance calcium-activated K channels (K(Ca)1.1) was examined. Voltage clamp assessed the role of K(V)7 channels in hypoxia. KEY RESULTS Gradual reduction of oxygen concentration from 95 to 1% dilated the precontracted coronary arteries and this was associated with reduced [Ca(2+)](i) in PGF(2α) (10 μM)-contracted arteries whereas no fall in [Ca(2+)](i) was observed in 30 mM K-contracted arteries. Blockers of ATP-sensitive voltage-gated potassium channels and K(Ca)1.1 inhibited hypoxia-induced dilatation in PGF2α -contracted arteries; this inhibition was more marked in the presence of the K(v)7 channel blockers, XE991 and linopirdine, while a K(V)7.1 blocker, failed to change hypoxic vasodilatation. XE991 also inhibited H₂S- and adenosine-induced vasodilatation. PCR revealed the expression of K(V)7.1, K(V)7.4, K(V)7.5 and K(Ca)1.1 channels, and K(Ca)1.1, K(V)7.4 and K(V)7.5 were also identified by immunoblotting. Voltage clamp studies showed the XE991-sensitive current was more marked in hypoxic conditions. CONCLUSION The K(V)7.4 and K(V)7.5 channels, which we identified in the coronary arteries, appear to have a major role in hypoxia-induced vasodilatation. The voltage clamp results further support the involvement of K(V)7 channels in this vasodilatation. Activation of these K(V)7 channels may be induced by H₂S and adenosine.
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Affiliation(s)
- E R Hedegaard
- Department of Biomedicine, Pulmonary and Cardiovascular Pharmacology, University of Aarhus, Aarhus, Denmark
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23
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Zhang X, Hughes BA. KCNQ and KCNE potassium channel subunit expression in bovine retinal pigment epithelium. Exp Eye Res 2013. [DOI: 10.1016/j.exer.2013.10.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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24
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Zhang X, Hughes BA. KCNQ and KCNE potassium channel subunit expression in bovine retinal pigment epithelium. Exp Eye Res 2013; 116:424-432. [PMID: 24416770 PMCID: PMC3934573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Human, monkey, and bovine retinal pigment epithelial (RPE) cells exhibit an M-type K+ current, which in many other cell types is mediated by channels composed of KCNQ α-subunits and KCNE auxiliary subunits. Recently, we demonstrated the expression of KCNQ1, KCNQ4, and KCNQ5 in the monkey RPE. Here, we investigated the expression of KCNQ and KCNE subunits in native bovine RPE. RT-PCR analysis revealed the expression of KCNQ1, KCNQ4, and KCNQ5 transcripts in the RPE, but, in Western blot analysis of RPE plasma membranes, only KCNQ5 was detected. Among the five members of the KCNE gene family, transcripts for KCNE1, KCNE2, KCNE3, and KCNE4 were detected in bovine RPE, but only KCNE1 and KCNE2 proteins were detected. Immunohistochemistry of frozen bovine retinal sections revealed KCNE1 expression near the apical and basal membranes of the RPE, in cone outer segments, in the outer nuclear layer, and throughout the inner retina. The localization of KCNE1 in the RPE basal membrane, where KCNQ5 was previously found to be present, suggests that this β-subunit may contribute to M-type K(+) channels in this membrane.
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Affiliation(s)
- Xiaoming Zhang
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI
| | - Bret A. Hughes
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, MI
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI
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25
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Verhoeven VJM, Hysi PG, Wojciechowski R, Fan Q, Guggenheim JA, Höhn R, MacGregor S, Hewitt AW, Nag A, Cheng CY, Yonova-Doing E, Zhou X, Ikram MK, Buitendijk GHS, McMahon G, Kemp JP, Pourcain BS, Simpson CL, Mäkelä KM, Lehtimäki T, Kähönen M, Paterson AD, Hosseini SM, Wong HS, Xu L, Jonas JB, Pärssinen O, Wedenoja J, Yip SP, Ho DWH, Pang CP, Chen LJ, Burdon KP, Craig JE, Klein BEK, Klein R, Haller T, Metspalu A, Khor CC, Tai ES, Aung T, Vithana E, Tay WT, Barathi VA, Chen P, Li R, Liao J, Zheng Y, Ong RT, Döring A, Evans DM, Timpson NJ, Verkerk AJMH, Meitinger T, Raitakari O, Hawthorne F, Spector TD, Karssen LC, Pirastu M, Murgia F, Ang W, Mishra A, Montgomery GW, Pennell CE, Cumberland PM, Cotlarciuc I, Mitchell P, Wang JJ, Schache M, Janmahasatian S, Janmahasathian S, Igo RP, Lass JH, Chew E, Iyengar SK, Gorgels TGMF, Rudan I, Hayward C, Wright AF, Polasek O, Vatavuk Z, Wilson JF, Fleck B, Zeller T, Mirshahi A, Müller C, Uitterlinden AG, Rivadeneira F, Vingerling JR, Hofman A, Oostra BA, Amin N, Bergen AAB, Teo YY, Rahi JS, Vitart V, Williams C, Baird PN, Wong TY, Oexle K, Pfeiffer N, Mackey DA, Young TL, van Duijn CM, Saw SM, Bailey-Wilson JE, Stambolian D, Klaver CC, Hammond CJ. Genome-wide meta-analyses of multiancestry cohorts identify multiple new susceptibility loci for refractive error and myopia. Nat Genet 2013; 45:314-8. [PMID: 23396134 PMCID: PMC3740568 DOI: 10.1038/ng.2554] [Citation(s) in RCA: 337] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Accepted: 01/16/2013] [Indexed: 02/06/2023]
Abstract
Refractive error is the most common eye disorder worldwide and is a prominent cause of blindness. Myopia affects over 30% of Western populations and up to 80% of Asians. The CREAM consortium conducted genome-wide meta-analyses, including 37,382 individuals from 27 studies of European ancestry and 8,376 from 5 Asian cohorts. We identified 16 new loci for refractive error in individuals of European ancestry, of which 8 were shared with Asians. Combined analysis identified 8 additional associated loci. The new loci include candidate genes with functions in neurotransmission (GRIA4), ion transport (KCNQ5), retinoic acid metabolism (RDH5), extracellular matrix remodeling (LAMA2 and BMP2) and eye development (SIX6 and PRSS56). We also confirmed previously reported associations with GJD2 and RASGRF1. Risk score analysis using associated SNPs showed a tenfold increased risk of myopia for individuals carrying the highest genetic load. Our results, based on a large meta-analysis across independent multiancestry studies, considerably advance understanding of the mechanisms involved in refractive error and myopia.
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26
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Kiefer AK, Tung JY, Do CB, Hinds DA, Mountain JL, Francke U, Eriksson N. Genome-wide analysis points to roles for extracellular matrix remodeling, the visual cycle, and neuronal development in myopia. PLoS Genet 2013; 9:e1003299. [PMID: 23468642 PMCID: PMC3585144 DOI: 10.1371/journal.pgen.1003299] [Citation(s) in RCA: 219] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2012] [Accepted: 12/18/2012] [Indexed: 11/18/2022] Open
Abstract
Myopia, or nearsightedness, is the most common eye disorder, resulting primarily from excess elongation of the eye. The etiology of myopia, although known to be complex, is poorly understood. Here we report the largest ever genome-wide association study (45,771 participants) on myopia in Europeans. We performed a survival analysis on age of myopia onset and identified 22 significant associations (), two of which are replications of earlier associations with refractive error. Ten of the 20 novel associations identified replicate in a separate cohort of 8,323 participants who reported if they had developed myopia before age 10. These 22 associations in total explain 2.9% of the variance in myopia age of onset and point toward a number of different mechanisms behind the development of myopia. One association is in the gene PRSS56, which has previously been linked to abnormally small eyes; one is in a gene that forms part of the extracellular matrix (LAMA2); two are in or near genes involved in the regeneration of 11-cis-retinal (RGR and RDH5); two are near genes known to be involved in the growth and guidance of retinal ganglion cells (ZIC2, SFRP1); and five are in or near genes involved in neuronal signaling or development. These novel findings point toward multiple genetic factors involved in the development of myopia and suggest that complex interactions between extracellular matrix remodeling, neuronal development, and visual signals from the retina may underlie the development of myopia in humans. The genetic basis of myopia, or nearsightedness, is believed to be complex and affected by multiple genes. Two genetic association studies have each identified a single genetic region associated with myopia in European populations. Here we report the results of the largest ever genetic association study on myopia in over 45,000 people of European ancestry. We identified 22 genetic regions significantly associated with myopia age of onset. Two are replications of the previously identified associations, and 20 are novel. Ten of the novel associations replicate in a small separate cohort. Sixteen of the novel associations are in or near genes implicated in eye development, neuronal development and signaling, the visual cycle of the retina, and general morphology: BMP3, BMP4, DLG2, DLX1, KCNMA1, KCNQ5, LAMA2, LRRC4C, PRSS56, RBFOX1, RDH5, RGR, SFRP1, TJP2, ZBTB38, and ZIC2. These findings point to numerous biological pathways involved in the development of myopia and, in particular, suggest that early eye and neuronal development may lead to the eventual development of myopia in humans.
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Affiliation(s)
- Amy K. Kiefer
- 23andMe, Mountain View, California, United States of America
| | - Joyce Y. Tung
- 23andMe, Mountain View, California, United States of America
| | - Chuong B. Do
- 23andMe, Mountain View, California, United States of America
| | - David A. Hinds
- 23andMe, Mountain View, California, United States of America
| | | | - Uta Francke
- 23andMe, Mountain View, California, United States of America
| | - Nicholas Eriksson
- 23andMe, Mountain View, California, United States of America
- * E-mail:
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27
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Spitzmaul G, Tolosa L, Winkelman BHJ, Heidenreich M, Frens MA, Chabbert C, de Zeeuw CI, Jentsch TJ. Vestibular role of KCNQ4 and KCNQ5 K+ channels revealed by mouse models. J Biol Chem 2013; 288:9334-44. [PMID: 23408425 DOI: 10.1074/jbc.m112.433383] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
The function of sensory hair cells of the cochlea and vestibular organs depends on an influx of K(+) through apical mechanosensitive ion channels and its subsequent removal over their basolateral membrane. The KCNQ4 (Kv7.4) K(+) channel, which is mutated in DFNA2 human hearing loss, is expressed in the basal membrane of cochlear outer hair cells where it may mediate K(+) efflux. Like the related K(+) channel KCNQ5 (Kv7.5), KCNQ4 is also found at calyx terminals ensheathing type I vestibular hair cells where it may be localized pre- or postsynaptically. Making use of Kcnq4(-/-) mice lacking KCNQ4, as well as Kcnq4(dn/dn) and Kcnq5(dn/dn) mice expressing dominant negative channel mutants, we now show unambiguously that in adult mice both channels reside in postsynaptic calyx-forming neurons, but cannot be detected in the innervated hair cells. Accordingly, whole cell currents of vestibular hair cells did not differ between genotypes. Neither Kcnq4(-/-), Kcnq5(dn/dn) nor Kcnq4(-/-)/Kcnq5(dn/dn) double mutant mice displayed circling behavior found with severe vestibular impairment. However, a milder form of vestibular dysfunction was apparent from altered vestibulo-ocular reflexes in Kcnq4(-/-)/Kcnq5(dn/dn) and Kcnq4(-/-) mice. The larger impact of KCNQ4 may result from its preferential expression in central zones of maculae and cristae, which are innervated by phasic neurons that are more sensitive than the tonic neurons present predominantly in the surrounding peripheral zones where KCNQ5 is found. The impact of postsynaptic KCNQ4 on vestibular function may be related to K(+) removal and modulation of synaptic transmission.
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Affiliation(s)
- Guillermo Spitzmaul
- Leibniz-Institut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), 13125 Berlin, Germany
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28
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Abstract
Photoreceptors are exquisitely adapted to transform light stimuli into electrical signals that modulate neurotransmitter release. These cells are organized into several compartments including the unique outer segment (OS). Its whole function is to absorb light and transduce this signal into a change of membrane potential. Another compartment is the inner segment where much of metabolism and regulation of membrane potential takes place and that connects the OS and synapse. The synapse is the compartment where changes in membrane potentials are relayed to other neurons in the retina via release of neurotransmitter. The composition of the plasma membrane surrounding these compartments varies to accommodate their specific functions. In this chapter, we discuss the organization of the plasma membrane emphasizing the protein composition of each region as it relates to visual signaling. We also point out examples where mutations in these proteins cause visual impairment.
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Affiliation(s)
- Sheila A Baker
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.
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Pattnaik BR, Hughes BA. Effects of KCNQ channel modulators on the M-type potassium current in primate retinal pigment epithelium. Am J Physiol Cell Physiol 2011; 302:C821-33. [PMID: 22135213 DOI: 10.1152/ajpcell.00269.2011] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Recently, we demonstrated the expression of KCNQ1, KCNQ4, and KCNQ5 transcripts in monkey retinal pigment epithelium (RPE) and showed that the M-type current in RPE cells is blocked by the specific KCNQ channel blocker XE991. Using patch-clamp electrophysiology, we investigated the pharmacological sensitivity of the M-type current in isolated monkey RPE cells to elucidate the subunit composition of the channel. Most RPE cells exhibited an M-type current with a voltage for half-maximal activation of approximately -35 mV. The M-type current activation followed a double-exponential time course and was essentially complete within 1 s. The M-type current was inhibited by micromolar concentrations of the nonselective KCNQ channel blockers linopirdine and XE991 but was relatively insensitive to block by 10 μM chromanol 293B or 135 mM tetraethylammonium (TEA), two KCNQ1 channel blockers. The M-type current was activated by 1) 10 μM retigabine, an opener of all KCNQ channels except KCNQ1, 2) 10 μM zinc pyrithione, which augments all KCNQ channels except KCNQ3, and 3) 50 μM N-ethylmaleimide, which activates KCNQ2, KCNQ4, and KCNQ5, but not KCNQ1 or KCNQ3, channels. Application of cAMP, which activates KCNQ1 and KCNQ4 channels, had no significant effect on the M-type current. Finally, diclofenac, which activates KCNQ2/3 and KCNQ4 channels but inhibits KCNQ5 channels, inhibited the M-type current in the majority of RPE cells but activated it in others. The results indicate that the M-type current in monkey RPE is likely mediated by channels encoded by KCNQ4 and KCNQ5 subunits.
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Affiliation(s)
- Bikash R Pattnaik
- Univ. of Michigan, Dept. of Ophthalmology and Visual Sciences, W. K. Kellogg Eye Center, Arbor, MI 48105, USA
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